Given the popularity of the 230/250 quads at the moment (blackout etc), I thought - wouldn't it be cool to have a rig that can do the ground skimming proximity stuff, but also with the normal "mod cons" of the APM?
Traditionally though, an APM would never fit. Until HK released the mini...so I built one.
I started with the Haldey-Bocks 230 frame, in Carbon Fibre. This was a mistake. I should have gone for the 250, because the fitting of the ESC's was a bitch of a job, especially with the thick 3DR power module hanging off it. And naturally, I forgot to solder in the XT for the video feed, so had to start again...
Anyway, this is the bare airframe:
So onto the fun part...
First, I fitted the camera, so I could make sure the clearances were good. I mounted it directly to the front CF plate to make sure I had as much room as possible behind it.
Second, I mounted the GPS antenna pole. This required a lot of trial and error, but eventually I found a position which worked.
Third, I fitted the APM mini in front of the post, and behind the camera. There is *just* enough room to do this. It is currently mounted with double 3M pads - I will review vibe damping after the first flight. Supposedly the blue balls do the "clean/dirty" thing, but is it enough to keep the APM within Z axis tolerances? Time will tell. These rcx are not the smoothest I have to say, and a propless spin up was really vibey.
I wired in the GPS, and the radio.
Then I mounted the 3DR telemetry radio to the roof. It is likely I will replace this with a minimOSD, and run a really simple OSD - volts, ground speed and home distance.
I then cable-tied the xt60 back on on itself on the PM - it was interfering with the props.
CoG is spot on, even though I thought it would be rearward.
Weight with tx will be 505 grams as you see it here. I have a wiring exercise to do (shorten and tidy), and to enclose the APM with some foam (for the Baro), and I hope that brings it down below the target 500 grams.
And that's it! It all fits together nicely. All the normal calibrations done - just compassmot to do (want to wait until I've got the camera and tx wired in first). Going for a really small 200mW 32ch 5.8. Will fit perfectly.
I didn't have time to get the thing in the air, but should able to get it in the air at the weekend. Can't wait to use DRIFT on this...:-)
Comments
Hey Shay, are you using a APM or a Pixhawk?
Thanks for the feedback everybody!!
The default imax is too low for this kind of fram with really "long" (I donno how to phrase it) center of gravity, one of the pitch sides with camera at the edge (sometime heavy gopro) on the other edge the battery, the imax says how much can be corrected, and with momentum its not enough, they are going to change the default to 1000 i think.
Change the LPF to 20hz back now. it autotunes and flies great, couldn't get althold or poshold to work on 42hz... guess too much vibrations, autotunes puts me in the right direction for the D term and ratios of pitch/roll but makes the quad way too soft, I have to add alot to the pids for it to be "razor sharp"
@Savet, you've been one step ahead of me during this whole build. Found your notes on the APM Forum. Changing my IMAX rates to 1800 solved the over correction problem. Off to the races for me. I'm good to go. :)
Starting to pick up the paces, my tuning falls short with aggressive stopping at high speeds, it pitches backwards and almost falls on itself. Had a long day tuning with no results. Video (stab mode) here, but also occurs in full acro: https://vimeo.com/104951291
APM / Copter is well balanced and calibrated front to back. My PIDs from an autotune:
https://www.dropbox.com/s/tqtd0kr8p5de3t2/ryan.png?dl=0
Any ideas?
So did another autotune on a much less windy day (still but windy but no gusts), got very different results: 0.003 D for roll and 0.00130 for pitch, pitch P i got 0.2!!!
I think autotune is set to give a calm vehicle, but I want to get a sharp and aggressive mini, so it gives me a good start, especially on the D value. did some acro, no Inversions after flips. the acro_expo on 0.4 (high) with acro_rp_rate 10 (max) works really good, if it was a tiddy bit higher it would be even better, maybe parentage selection.
But no oscillations even after i raised the second autotune values (roll only) , great work!!
This is great. Any autotune vids?
Promising so far!
Keep the feedback coming.
Thanks!
Did rc5 today as well – ran a quick PID tune and no oscillations @ 42 Hz. Put it down the street and back. Flies like a razor blade. Thank you APM community. Let the races begin.
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